Designers of printed circuit boards (PCBs) and other circuit substrates endeavor to increase the functionality and capacity thereof. One enabling factor of this pursuit is the provision of more conductive traces that go from side to side and from layer to layer and in this way form interconnections between active electronic elements that are mounted on the PCB.
A common material PCB material in use is a glass-epoxy-based laminate with the PCBs being built in single-sided, double-sided, and even multilayer configurations. The laminate serves as an insulator between the adjacent conductive traces on the surface of the PCB (in single-sided and double-sided configurations), as well as between the multiple layers of conductive traces within the PCB (in multilayer configurations).
Electrical traces on different levels are connected by forming a hole in the laminate between the layers, and then plating the interior surface of this hole with a conductive material to form a “via”.
As data and signal speeds have increased in PCBs, various challenges have arisen. One challenge is the carrying of a high frequency signal over a simple conductive trace on the surface of a PCB. Another challenge is the potential for electromagnetic interference between the signals carried on multiple conductive traces on the same PCB.
Yet another challenge lies in excessive electromagnetic radiation emanating from a PCB, which is produced by the high frequency signals carried by simple conductive traces on (or in) the PCB. This excessive emanation of electromagnetic radiation is undesirable for a variety reasons. First, it is a potential source of interference with other electronic equipment within an electronic device. In addition, it may also present a security problem since such emanation of electromagnetic radiation is susceptible to being intercepted and decoded by hostile parties.
Consequently, the development of advanced ways of shielding vias, conductive traces, and components of and on a PCB is desirable.